This invention generally relates to a catheter apparatus for controllably anchoring and stabilizing a catheter tip relative to a selected tissue.
Medical analysis for the heart muscle has revealed that each normal heart contraction occurs as the result of electrical impulses in the form of a depolarization wave spreading from the atrium to the muscular tissue of the ventricle. In the event that various cells within the heart tissue have been damaged, propagation of the depolarization wave across the heart may be obstructed, leading to irregular heart beat and a condition known as cardiac arrhythmia.
Advances in medical technology for the treatment of cardiac arrhythmia have resulted in the development of various procedures for investigating and remedying the heart's irregular electrical activity. These modern procedures may utilize catheters that are percutaneously introduced into the patient through an artery to the atrium or ventricle of the heart to perform singular or multiple diagnostic, therapeutic, and/or surgical procedures. These catheter devices typically include multiple lumina, or longitudinal passageways, used for different purposes such as carrying electrical wires, body fluids, or drugs.
One medical procedure is known as electrophysiological mapping where a physician analyzes the depolarization waveforms as they propagate across the heart during each contraction. A percutaneously introduced steerable catheter mapping device may be utilized to position an electrode or electrodes for systematically scanning selected endocardial sites within the heart to detect propagation of wave electrical impulses. Through the detection of irregular electrical impulses, the locations of damaged cells may be revealed. Once these damaged cells have been located, the physician may use an ablation procedure to destroy the damaged cells in an attempt to remove the depolarization wave obstruction and bring about a more normal heart beat. The ablation device may be incorporated in the catheter along with the mapping device.
In order for mapping procedures to be effective, the electrode must be precisely located with respect to the tissue and preferably make intimate contact with the endocardial tissue during systematic scanning over various sites. Due to the heart's periodic contraction such precise location is difficult to maintain. This is particularly true when the patient's heart experiences rapid movement during, for instance, tachycardia. Typical procedure requires the physician to manually apply continual axial pressure to the proximal end of the catheter forcing the catheter distal end against the tissue site.
Many catheter ablation devices use radio frequency (RF) technology to destroy damaged endocardial cells. In practice, the catheter distal tip is fitted with an electrode which will emit RF energy to destroy located damaged cells. To be most effective, the electrode at the distal end of an RF ablation catheter is placed in secure intimate contact with the selected endocardial tissue in order to avoid leaving a gap in which concentrated energy might boil the blood in the intracardial volume. Positive maintenance of intimate electrode to tissue contact is further effective to better focus the RF energy to the selected site limiting unnecessary tissue ablation. Positioning of the electrode relative to the tissue can best be achieved by anchoring to the tissue and then shifting the electrode relative to the anchor point. It is desirable to align the catheter tube and attached distal electrode in a perpendicular position relative to the target tissue site so as to accurately discharge RF energy which further limits unnecessary tissue ablation.
Hence, those skilled in the art have recognized the need for anchoring a catheter distal tip to a selected endocardial site. Furthermore, recognized benefits inure in repeatedly positioning and anchoring the catheter distal tip relative to several endocardial sites within a patient's intracardial volume.